MR IMAGING OF THE RETROPERITONEUM

Retroperitoneal Sarcomas

BACKGROUND

The evaluation and treatment of retroperitoneal sarcomas are challenging because the tumors are relatively rare and frequently present with advanced disease in an anatomically complex location.

METHODS

We reviewed the literature on experience in the management of retroperitoneal sarcomas, and we present our own experience in the treatment of these tumors.

RESULTS

The identification of prognostic factors other than the adequacy of resection has been inconsistent. Due to a lack of associated symptoms, retroperitoneal sarcomas smaller than 5 cm are rare. Computed tomography is the most useful tool in the evaluation of retroperitoneal tumors. Surgery, radiation therapy, and chemotherapy are treatment options, but the most important factor in the treatment of primary tumors is complete surgical resection. The role of neoadjuvant and adjuvant therapies is not defined and should be considered within the context of clinical trials.

CONCLUSIONS

Early referral of patients with retroperitoneal soft tissue tumors will help to ensure that they will receive the benefits of multidisciplinary evaluation and treatment of their disease and ready access to clinical trials.

Primary malignant tumors of peritoneal and retroperitoneal origin: clinical and imaging features

Peritoneal carcinomatosis and metastatic involvement of the retroperitoneum are manifestations of many organ-based malignancies and lymphoproliferative disorders. Primary malignancies of peritoneal and retroperitoneal origin occur much less frequently, and are difficult to distinguish from metastatic disease on imaging alone. However, the imaging features of these primary tumors, taken in concert with the clinical data, can be helpful in narrowing the scope of the differential diagnosis. This review presents the clinical and imaging features of primary peritoneal and retroperitoneal tumors arising from the various tissue components that comprise the ligaments, mesenteries, and connective tissues of the peritoneal and retroperitoneal spaces.

Retroperitoneal neoplasms within the perirenal space in infants and children: differentiation of renal and non-renal origin in enhanced CT images

PURPOSE

To retrospectively demonstrate the specific CT findings of retroperitoneal neoplasms to diagnosis and differential diagnosis renal and non-renal tumors within the perirenal space in infants and children.

MATERIALS AND METHODS

We retrospectively reviewed the clinical data and CT images of 42 consecutive patients with surgically and pathologically proven retroperitoneal neoplasms within the perirenal space. The patients were divided into renal tumors group (n=16) and non-renal tumors group (n=26). The former included nephroblastoma (n=15) and renal lymphoma (n=1), while the latter included neuroblastoma (n=12), retroperitoneal teratoma (n=6), adrenal ganglioneuroma (n=4), retroperitoneal lymphoma (n=2), ectopic pheochromocytoma (n=1) and adrenal cortical carcinoma (n=1). The clinical information of these patients and the major CT imaging findings which were related to lesion localization in the two groups were compared and statistically analyzed using Pearson Chi-Square Test and Risk Estimate.

RESULTS

The mean diameter of tumors was 9.82±6.13 cm (n=42 range: 2.3-3 2cm). The demographic data and chief clinical symptoms between the renal tumor group and the non-renal tumor group showed no statistically significant differences (P>0.05). 30.8% (8/26) of non-renal tumor patients presented elevated urinary vanillylmandelic acid (VMA) level, while no patient showed elevated VMA in renal tumor group (P<0.05). Some CT imaging signs of the renal tumors including "crescent sign" (odds ratio, OR=52), "beak sign" (OR=84), "embedded organ sign" (OR=84), and "prominent feeding artery sign" (OR=36) showed significantly higher incidence when compared to the non-renal tumors (P<0.001). The sign of "renal displacement and renal axis rotation" (OR=0.059) was seen in 23 of 26 (88.5%) non-renal tumors, but in only 5 of 16 (31.3%) renal tumors (P<0.001). The sign of "extra-renal central plane of tumor" (OR=0.038) was displayed in 24 of 26 (92.3%) non-renal tumors, but in only 5 of 16 (31.3%) renal tumors (P<0.001). The CT findings such as "pseudocapsule" (OR=38.5), "necrosis and cystic change" (OR=11.2), "vascularity" (OR=16.867), "distant metastasis" (OR=5.96), and "inferior vena cava tumor thrombus" which were thought to be characteristic of renal tumors were observed with significant higher incidence in renal tumors group than in the non-renal tumors group (P<0.05); while CT signs of "irregular mass" (OR=0.045) and "intratumoral calcifications" (OR=0.065) were observed with lower incidence in renal tumors group than in the non-renal tumors group (P<0.05).

CONCLUSION

The "crescent sign", "beak sign", "embedded kidney sign" and "renal arteries feeding" are the most specific CT signs suggestive of renal tumors and distinguish them from non-renal origin tumors within the perirenal space. Other CT signs, such as "pseudocapsule", "hypervascular tumors" and "Inferior vena cava tumor thrombus", when present, tumors of renal origin are strongly suggested. On the other hand, CT signs of "irregular mass", "intratumoral calcifications", and associated elevated urinary vanillylmandelic acid strongly suggest the non-renal tumors.

Primary retroperitoneal neoplasms: CT and MR imaging findings with anatomic and pathologic diagnostic clues

Primary retroperitoneal neoplasms are a rare but diverse group of benign and malignant tumors that arise within the retroperitoneal space but outside the major organs in this space. Although computed tomography and magnetic resonance imaging can demonstrate important characteristics of these tumors, diagnosis is often challenging for radiologists. Diagnostic challenges include precise localization of the lesion, determination of the extent of invasion, and characterization of the specific pathologic type. The first step is to determine whether the tumor is located within the retroperitoneal space. Displacement of normal anatomic structures of the retroperitoneum is helpful in this regard. For tumors that are located within the retroperitoneum, the next step is to identify the organ of origin. Specific signs, including the "beak sign," the "embedded organ sign," and the "phantom (invisible) organ sign," are useful for this purpose. When there is no definite sign that suggests the organ of origin, the diagnosis of a primary retroperitoneal tumor becomes likely. Awareness of specific patterns of spread, specific tumor components, and tumor vascularity help in further narrowing the differential diagnosis. Attention to these diagnostic clues is essential in making an accurate radiologic diagnosis of primary retroperitoneal tumors and in obtaining clinically significant information.

Soft tissue carcinoma in the retroperitoneum: an often neglected diagnosis

AIMS

Successful surgical treatment of patients with retroperitoneal soft tissue sarcoma (RSTS) is based on pre-operative planning that starts with a correct pre-operative diagnosis. In a population-based study, we determined which patients were initially treated for assumed other conditions. The effect of an erroneous diagnosis on the installed treatment was analysed.

METHOD

With the help of the Dutch Network and National Database for Pathology (PALGA), data were collected on 143 patients in the Netherlands in whom a primary RSTS was found and confirmed histologically between 1 January 1989 and 1 January 1994. Satisfactory clinical information was obtained on 138 patients, 64 males and 74 females (54%). The median age was 60 (range 18-88) years.

RESULTS

At the time of actual treatment 37% of the patients with RSTS were assumed to have another disorder (group 1 n=51), whereas 87 patients were diagnosed as having RSTS (group 2). In group 1, an acute presentation was more common (18 vs 2% P=0.002), and the tumour was less often palpable at physical examination (43 vs 69% P=0.004), while clinical work-up less frequently included CT-imaging (57 vs 89% P<0.001) and a biopsy (29 vs 77% P<0.001). Although tumours in group 1 were smaller (median diameter 13 vs 19 cm P<0.05), this was not reflected in a better operative result: less patients underwent complete tumour resection (51 vs 57%) and more patients underwent surgery for tumours that proved to be irresectable (14 vs 1% P=0.004).

CONCLUSIONS

(1) More than one-third of patients with RSTS are misdiagnosed and inappropriately treated; and (2) biopsies and cross-sectional imaging improve diagnosis.